It's a thing in maths that stuff gets named after whoever people decide at the time deserves it, not necessarily the person who discovered it.

General Taylor series were discovered by James Gregory (long after the first Taylor series for sine and cosine etc were written down by Madhava of Sangamagrama) who taught them to Maclaurin who taught them to Taylor.

Lambert's W function (also known as the product log function) was the function that Euler discovered that solved a problem that Lambert couldn't solve.

Gauss' law in physics was discovered by Lagrange. In turn, Lagrange's notation for derivatives was used by Lagrange, but was invented far earlier by Euler.

"Feynman's Trick" in calculus of parameterizing and then differentiating under the integral was also discovered by Euler. Like yeah. 250 years isn't enough to stop someone stealing the name of something you discovered. I think Euler discovered so many things people just decided at some point they couldn't name everything after Euler so started giving other people a chance.

The Gaussian distribution was discovered by de Moivre. Gaussian elimination was in textbooks in the time of Gauss so in his work he calls it "common elimination".

Arabic numerals were invented by Indian mathematicians.

Practically the only thing we know for absolute certain about Pythagoras is that he didn't discover Pythagoras' theorem (that had been known to the Babylonians centuries earlier).

Bayes never published his paper during his lifetime but it involves a very important thought experiment in probability and not the equation that everyone knows as Bayes' theorem, which was actually written by Laplace after reading Bayes paper.

Cantor didn't discover the Cantor set.

etc etc. There are hundreds or possibly thousands of examples. This is known as Stigler's law. https://en.wikipedia.org/wiki/Stigler's_law_of_eponymy

There are two more fun examples then I’ll stop. Kuiper published a paper stating that a ring of asteroids didn’t exist in the solar system. So when such a ring was discovered naturally it was named the Kuiper belt after him. Not maths, but in the same vein, in chess an early theorist called Damiano published an analysis showing that 1 e4 e5 Nf3 f5 was losing for black, so now that’s called “Damiano’s defence “

Funniest but is that Stigler was not the first to discover Stigler's law.

Fibonacci series goes far far back in time than Leonardo of Pisa.

Most of these fall under the math version of Darwin's Law?

>In science the credit goes to the man who convinces the world, not to the man to whom the idea first occurs.

  -- in Eugenics Review April 1914 ‘Francis Galton’

That was great reading, thank you! TIL